"There's basic limitations in what our brain can do. So there's only so much information we can hold in mind at the same time," Gazzaley said.

In their new book, "The Distracted Mind," Gazzaley and his co-author Larry D. Rosen argue that human brains were never evolved to multi-task. He says when we concentrate on one thing the part of our brain that handles abstract thinking does much of the heavy lifting. But when we're absorbing multiple sources at once, it's forced to switch back and forth.

"And with each of those switches, there's a loss of the high-resolution of that information," he says.

The result: everything from sloppier work to slower response times. There's new evidence it's habit forming. Dr. Gazzaley says one recent study found young adults typically switch tasks every two minutes.

But what can you do in a digital age, where we have so many demands on our time? Turns out the advice isn't to ditch technology, just manage it differently. Researchers say you must prioritize important tasks, and concentrate on them until their done.

"If I have a project that just needs to get done, that's not the time to switch back and forth between Twitter and Facebook and a phone call," advises Gazzaley

He also says to set digital down time, where you don't talk on the phone, text or read emails. Let family, friends and colleagues know you're unavailable. And finally, clear your mind before or after a task with exercise or meditation.

"Practice the art of attention. If you practice it and get better at it, I think you'll see the benefits," said Gazzaley.

And he believes the reward of single-tasking, could actually be a more balanced and productive life.

The research team says even short micro-distractions from all our devices can cause symptoms that mimic forgetfulness. In reality they say we haven't forgotten what we intended to do, we just lost track of it.